Whooping cough (or pertussis) is a current problem in public health and an important cause of death among children, including countries with a high level of vaccination. This is a bacterial disease mainly caused by Bordetella pertussis, and also by B. parapertussis. Estimates by the World Health Organization (WHO) indicate that in 2008 there were close to 16 million cases of whooping cough worldwide, 95% of which were located in developing countries, and around 195,000 children have died as a result of this disease.
Child immunization programs with a vaccine against whooping cough have been successful in preventing a serious disease. But in the last decades, the disease has reappeared with characteristic outbreaks occurring every two to three years, with a surprisingly high number of cases not only among the infant population, but also among adolescents and adults.
The scientific community and healthcare professionals have focused their activities on the search to ascertain the causes for the resurgence of the disease, as well as on the review and application of new strategies to enhance disease control. As to the causes that might explain this resurgence of the disease, various explanations have been proposed, most of which are related to the vaccines currently in use (He, Q., J. Makinen, et al. J. Infect. Dis. 187:1200-1205, 2003 and Mooi, F. R., et al. Emerg. Infect. Dis. 7:526-528, 2001).
In this context, besides optimizing the use of existing vaccines, the development of new and enhanced vaccines is urgent. In this regard, it is important to remember that there are two types of vaccines: a) cellular vaccines constituted by a suspension of whole bacteria destroyed by heat and detoxified: b) acellular vaccines (also known as subunit vaccines) consisting of purified protein immunogens (3 or 5) of B. pertussis. There are pediatric formulations for acellular vaccines, as well as formulations aimed at adolescents and adults. It is important to point out that none of the present day formulations contain any components deriving from B. parapertussis. Moreover, these formulations do not confer any adequate protection against this etiological agent of the whooping cough (Cherry, J. D., et al. 2008-2010. Clin. Infect. Dis. 54:534-53715).
Subunit vaccines (nonreplicative systems, also known as acellular vaccines) are particularly attractive among traditional vaccine designs, given that they induce a protective immune response, thus avoiding the limitations on biosafety of any of the attenuated vaccines or vaccines made of whole dead microorganisms. Despite its advantages in terms of safety, a major limitation of subunit antigens is their inability to stimulate strong in vivo immune responses when administered alone.